It has been demonstrated that abnormal levels of PMP22 expression due to altered gene dosage in CMT1A neuropathy alters Schwann cell growth and differentiation. On the other hand, disease‐related missense mutations within transmembrane domains of PMP22 disturb intracellular protein trafficking leading to accumulation of the mutant protein in the endoplasmic reticulum/Golgi compartment. Further, the recently reported association of PMP22 and P0 in peripheral myelin sheds new light on the almost identical phenotypes of CMT1A and CMT1B giving rise to a unifying hypothesis on disease mechanism. GLIA 29:182–185, 2000. © 2000 Wiley‐Liss, Inc.